Diag:Diagonal matrices and diagonals of a matrix

Syntax

X = diag(v,k)

X = diag(v)

v = diag(X,k)

v = diag(X)

Description

X = diag(v,k) when v is a vector of n components, returns a square matrix X of order n+abs(k), with the elements of v on the kth diagonal. k = 0 represents the main diagonal, k > 0 above the main diagonal, and k < 0 below the main diagonal.

X = diag(v) puts v on the main diagonal, same as above with k = 0.

v = diag(X,k) for matrix X, returns a column vector v formed from the elements of the kth diagonal of X.

v = diag(X) returns the main diagonal of X, same as above with k = 0.

example_

diag([1 2 3],-2) % 此时k=-2，注意黑色的部分

ans =

0 0 0 0 0

1 0 0 0 0

0 2 0 0 0

0 0 3 0 0

diag([1 2 3],2) % 此时k=2，注意黑色的部分

ans =

0 0 1 0 0

0 0 0 2 0

0 0 0 0 3

0 0 0 0 0

diag([1 2 3]) % 此时k=0，直接返回对角矩阵

ans =

1 0 0

0 2 0

0 0 3

diag([1 2 3;4 5 6; 7 8 9 ]) %若输入矩阵，返回对角

ans =

巴特西

Diag:Diagonal matrices and diagonals of a matrix

example_

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